That's one of the reasons x86 virtualization has become so important, but it still lags significantly behind the technology available on IBM's mainframes and Power systems, in Rymarczyk's opinion. One reason is that with mainframes and Power servers, virtualization isn't an optional add-on -- it's part of the system's firmware. "It's sort of routine for customers on our Power servers to be running 40 or 50 virtual machines or LPARs [logical partitions] concurrently, and many of these virtual machines may be mission critical," he says.

Simply creating VMs is just the tip of the iceberg, though. Rymarczyk says tomorrow's data center "needs robust I/O virtualization, which we've had on the mainframe for decades." But he does credit VMware with being the first to introduce live migration, the ability to move a VM from one physical host to another without suffering downtime. Live migration is a key enabler of cloud computing because it helps ensure high availability and gives IT pros extra flexibility in the deployment of VMs.

While IBM is a major producer of x86 servers, Big Blue has no plans to develop its own x86 hypervisor. But IBM is trying to position itself as one of the leaders in using virtualization technology to make tomorrow's data center more scalable and efficient.

"You're going to see the hypervisor on x86 essentially become free and there will be multiple choices," Rymarczyk says. "Open source, VMware, Microsoft, maybe even something from Intel that comes with the platform. There's little reason [for IBM] to invest in trying to make money by building a better [x86] hypervisor. Where the real opportunity exists in adding value for data centers is much higher up the stack."

IBM and VMware have advanced similar concepts that leverage virtualization technologies to aggregate data center resources into small numbers of logical computing pools that can be managed from single consoles. VMware just announced which it calls a "cloud operating system," while Rymarczyk at IBM came up with "Ensembles." Similar to Parallel Sysplex on the mainframe, Ensembles seeks to pool together compatible servers and automatically move virtual resources around the pool as needs change.